The wave of low-pricing and a miniaturization of a personal computer used by individual person is remarkable according to a development of the computer. Such a personal computer is used also at a home only as a tool of an office work. For this reason, it is required that it should have a function as home electronics apparatus in the personal computer. For example, in a personal computer, it has the function that reproduces image picture disks, such as DVD, and the function to perform games, such as CD.
Pictures, such as such an image, are usually displayed on the display screen of a personal computer. However, the personal computer is developed for the purpose of small and low-pricing, and the screen size is about 15 inches from 14 inches at maximum. On the other hand, the television and the projector that are used in a home or office have the tendency of big-screen, and that of 40 inches and 50 inches has appeared.
For this reason, it is required to not only display a picture on the small screen of a personal computer, but also to display the processing picture of a personal computer on an external large-sized display device. In order to realize this, the external display connection port is provided to the personal computer, and the processing picture is displayed on large-sized television by connecting the television to this port.
This method is for display the whole display screen of a personal computer on the external display. On the other hand, a personal computer processes two or more tasks concurrently, and displays two or more each tasks on one display screen in the form of a window.
For this reason, since two or more windows are displayed on an external display when making two or more tasks run, it occurs a problem that it cannot display only one window on the external display of a big screen during multitasking execution. For example, the window screen of other unnecessary tasks is also displayed on a big-screen of a by television during multitasking execution even though wanting to enjoy the reproduction picture of DVD, Video-CD with a big-screen television.
On the contrary, in order to display only one window on a big screen display, it is necessary not to start or to end processing of other tasks, and it occurs the problem that precious multitasking and a multi-window function of the personal computer cannot be used. For example, a transmission display of E-mail or WORD processing cannot be performed during reproduction of DVD.